2.0 Analysis 2.1 General The pilot was trained and experienced in slung-load operations and vertical-reference flying, and he had dealt proficiently with the mission throughout the day. The operation had proceeded smoothly until after the aircraft departed the island staging area on the final leg. Weather conditions were suitable for the operation. The investigation did not reveal any pre-existing mechanical discrepancies that could have led to the occurrence. A radio call made minutes before the accident indicates that the pilot believed that the aircraft was functioning normally. The absence of any distress call from the pilot suggests that the onset of the accident was sudden and severe and that there was no opportunity to make a distress call. While slinging, one of the first considerations during a critical emergency is to jettison the slung load. The load was not jettisoned before the aircraft contacted the water, further suggesting that there was no emergency condition of which the pilot was aware and that the accident involved a sudden and severe initiating event. 2.2 Load/Water Contact The loss of the hook assembly toward the rear of the aircraft, the disruption of flight controls around the hook assembly, the occurrence of mast bumping, and the suddenness of the accident are circumstances consistent with the load contacting the water. For load/water contact to occur, the helicopter would have had to descend after departing the island. However, the investigation was not able to ascertain the aircraft's flight profile during this portion, and no reason for descent was established. 2.3 Mast Bumping A characteristic of in-flight rotor/mast separation accidents is the differing resting locations of the rotor and the airframe. After separation, the airframe descends ballistically on its last track. The rotor, however, may continue to fly a substantial distance before impact. In this occurrence, the location of the main rotor within the debris field suggests that the rotor/mast separation took place at a low altitude. The flight profile did not require low-G manoeuvres, and it is unlikely that an experienced pilot would inadvertently induce low rotor loading during a routine mission over a flat surface. It is likely that drag forces from the load/water contact caused a sudden aircraft upset, mast bumping, and main-rotor separation. In-flight damage to the flight controls caused by the hook assembly tearing away could have contributed to excessive flapping angles and may also have prevented the pilot from recovering from the sudden aircraft upset. 2.4 Safety Harness Use Because of the severe impact forces, a shoulder harness would not have saved the pilot's life, even if it had been used. Nevertheless, external load operations involve increased risk, and use of available safety equipment would seem to be in order. This and other accidents involving vertical-reference operations have shown that the seat belt and shoulder equipment provided is ill-suited to the task of vertical-reference flying during external load operations. Pilots performing these types of flights should not need to shed available and required protective equipment in order to perform a task involving increased risk. 2.5 Survival Equipment - Flights Over Water Regulations for survival equipment are based on time and distance to an emergency landing site. For a person immersed in frigid water, however, flying time and distance are irrelevant. The major factor is being able to survive in the water until the life raft is inflated and/or until rescue arrives. Because survival equipment requirements are based on time and distance criteria, the carriage of adequate equipment is not ensured even though the dangers of sudden immersion in cold water are serious and immediate. Requirements for immersion suit use should be independent of the requirement to carry a life raft and should be based on factors such as the type of aircraft, type of operation, water temperature, air temperature, flight time from shore, and potential rescue time. The criteria should also recognize the potential effects of heat stress from wearing immersion suits during flight operations and should include guidance on this matter. 2.6 Underwater Locator Beacons The expeditious location of underwater aircraft wreckage is important for humanitarian reasons and is essential for investigative purposes. Examination of aircraft wreckage is a fundamental part of an accident investigation, and it is particularly important in those accidents where a recorder has not been installed on an aircraft and/or the crew do not survive. An underwater locating device, installed and operating, would likely have led to the wreckage being located more quickly. 3.0 Conclusions 3.1 Findings as to Causes and Contributing Factors During departure from the island, the helicopter descended, for undetermined reasons, to an altitude that allowed the load to contact the water. Drag forces on the hook assembly during load/water contact resulted in loss of the hook assembly, disruption of flight controls, loss of aircraft control, and rotor/mast separation. 3.2 Findings as to Risk The pilot did not wear the required shoulder harness or life jacket because these items interfered with his ability to conduct the vertical reference operation. This is a common practice among pilots who are required to perform these operations. Immersion suits were not required by regulation and were not worn, and the pilot did not have ready access to the on-board life raft. In a less-severe ditching occurrence, such items could increase survivability. Recovery of the aircraft was delayed because it was not equipped with an underwater locator beacon. Such equipment was not required by regulation. 4.0 Safety Action 4.1 Action Taken 4.1.1 Underwater Locator Beacon Installation On 06 November 2000, the TSB forwarded an Aviation Safety Information Letter to Transport Canada (TC) suggesting that other carriers with a high level of exposure to over-water operations consider the installation of an underwater locator beacon in their aircraft not equipped with flight data recorders. TC responded on 12December 2000, indicating that an article will be published in the newsletter Aviation Safety Letter to reflect this suggestion to industry. An article was published in Issue4/2001 of Aviation Safety Letter on the installation of an underwater locator beacon. TC has undertaken to install underwater beacons on all helicopters that operate in support of the Canadian Coast Guard, regardless of passenger seating capacity. 4.1.2 Safety Harness Use On 20 February 2001, the TSB forwarded an Aviation Safety Advisory to TC asking that consideration be given to investigating and requiring other means of personnel restraint for use during vertical-reference operations. TC responded to this advisory on 02May 2001, stating, in part: . . . The certification requirements for pilot restraint systems are described in Airworthiness Manual (AWM) 527 and 529. Since July1, 1986 (AWM First Edition) paragraph785 has required that Each pilot's seat must have a combined safety belt and shoulder harness with a single-point release that allows the pilot, when seated with the safety belt and shoulder harness fastened, to perform all of the pilot's necessary functions. This requirement has been retroactively imposed upon all rotorcraft manufactured after September16, 1992 regardless of certification basis (AWM527.2 and 529.2). In addition, CAR702.44 requires all Aerial Work aircraft to have the pilot seat and any seat beside the pilot seat equipped with a shoulder harness and CAR605.27 (3) requires that at least one pilot shall keep a safety belt fastened at all times. Transport Canada's mandate is to regulate safe aviation operations. Transport Canada has approved safe pilot restraint systems and has promulgated regulations regarding their installation and use. It is the responsibility of the industry to comply with the regulations, and if warranted, apply for an approval of a configuration to meet its operational needs. The Board agrees that it is the responsibility of the industry to comply with the regulations. However, the approved shoulder harnesses do not allow the pilot to perform all of the pilot's necessary functions, as stated above. The Board believes that further consideration of this issue is warranted by TC. 4.1.3 Survival Equipment - Flights Over Water On 26 February 2001, the TSB forwarded an Aviation Safety Advisory to TC asking that consideration be given to revising the criteria for survival equipment carriage, and use on over-water flights. TC responded on 02 April 2001, indicating that a working group has been convened to examine the issue of offshore operations and make recommendations. The working group will consider, inter alia, the requirements for the carriage of survival equipment, survival equipment use, and the accessibility of the equipment.